Then you lose your database quickly, so it’s still fast

It in Elon's case, catches fire and locks you in

My use case is primarily real time data capture - raw log is written to disk and can be recovered from, although at that point we'd have fallen back on the secondary as primary would now be suspect.

At which point you have to slurp down a few hundred terabytes from the other datacenters when the power turns back on.

This is why Google datacenter managers hesitate to turn off the power even when an employee is in the process of getting electrocuted.